This invention relates to actuator arms for computer hard disk drives, and more particularly relates to suspensions for micro actuators positioned on the ends of such actuator arms.
Computer hard disk drives typically include one or more rigid magnetic disks that spin during operation. Each disk has an associated actuator arm that is controlled to move across the disk so as to allow a slider, positioned at the end of the actuator arm, to move to a desired track so that a read/write head mounted on the slider is able to read or write data from the track. In recent years, in response to demands for ever increasing data densities and ever increasing data transfer rates, the slider has been mounted on a movable spring assembly coupled to the actuator arm by collinear longitudinal arms integral with the assembly and on either end thereof. The structure permits rotation of the spring assembly, and thus the slider/head assembly, about the axis of the longitudinal arms, and thereby minimizes torsional vibrations that propagate along the actuator arm. An example of this is described in U.S. Pat. No. 5,381,288, which issued on Jan. 10, 1995, to Raymond M. Karm, II, and was assigned to Applied Magnetics Corporation, Inc.
More recently, a micro actuator has been mounted on the end of the actuator arm and coupled to the arm by a compliant suspension. The micro actuator serves as a secondary actuator, and has the benefit of having a greater bandwidth than the primary actuator arm. An example of this is described in Miu et al., xe2x80x9cSilicon Microstructures and Microactuators for Compact Computer Disk Drives,xe2x80x9d Article presented at the Proceedings of the 14th IEEE Symposium on Mass Storage Systems, 1995. (See also U.S. Pat. No. 5,778,513, which issued on Jul. 14, 1998, to Denny K. Miu.) The arrangement disclosed in this article includes a xe2x80x9cpiggyback microactuatorxe2x80x9d that includes a silicon microgimbal. The microgimbal is an integral silicon structure that includes a central slider/platform portion disposed within an outer frame portion. The slider portion and the frame portion are connected together by way of four serpentine suspension springs which serve as fixed-fixed beams. Miu states that helical springs would be xe2x80x9can obvious solutionxe2x80x9d to the problem of providing suspension springs, but proposes the serpentine planar microsprings as a practical alternative.
However, the serpentine suspension springs proposed by Miu are complex structures and therefore difficult to design specific characteristics and to make subsequent adjustments to the suspension dynamics. In addition, the directional stiffness pattern is not optimal for such an application, allowing excessive vibrations in the non-motor direction, for example.
Other serpentine suspension spring arrangements are described in U.S. Pat. No. 5,847,902, which issued to Clifford, Jr., et al., on Dec. 8, 1998, and U.S. Pat. No. 5,882,532, which issued to Field et al., on Mar. 16, 1999, both of which were assigned to Hewlett-Packard Company. These arrangements suffer basically the same problems and limitations as the Miu et al. arrangement.
Therefore, there is a need for an improved suspension for a microactuator on a hard drive actuator arm. Further, there is a need for an improved suspension that allows easier design of specific characteristics and subsequent adjustments the suspension dynamics. Still further, there is a need for an improved suspension having stiffness characteristics more optimally suited to a micro actuator for a hard drive actuator arm. In addition, there is a need for improved suspension having an improved directional stiffness patterns.
These needs are substantially met by the present invention.
In accordance with the present invention there is provided an integral computer hard drive microactuator support comprising a unitary member of solid material. The support includes a frame portion surrounding and defining an opening portion, and a platform portion disposed within the opening portion. Four fixed-fixed beam portions connect the platform portion to the frame portion, the fixed-fixed beam portions being generally rectangular in cross section and substantially straight along their length.
These and other features of the invention will be apparent to those skilled in the art from the following detailed description of the invention, taken together with the accompanying drawings.